It is known in the building trade to use various types of below grade foundations for houses, parking garages, office buildings, hospitals, hotels and the like. Included in these foundations are poured concrete foundations, cinder block foundations and permanent wood foundations. Conventional block or poured concrete footers and walls form a solid mass impeding water flow from below-grade sources entering the interior of the building, i.e. such as cellars of homes, etc. Ground water therefore accumulates against the foundation in voids left from ground water which accumulates both during and after construction. This water could easily cause cracks in the foundation walls during freezing and thawing which eventually causes cracks and moisture problems in the cellar. Mildew forms because water accumulates causing humidity and odor problems in the interior of the structure.
There are a number of systems or structures that have been proposed for reducing or treating water accumulation along building structures such as those disclosed in U.S. Pat. Nos. 3,871,140; 4,523,875; 4,574,541; 4,612,742; 5,056,281; 5,120,162; 5,158,501; 5,228,805 and 5,248,225. None of these systems provides the desirable results of the present invention.
To minimize water problems, builders and engineers have suggested the use of porous crushed stone which permits below-grade water to flow through the stone, which acts as a storm drain. This expedient has been somewhat successful but not totally, because the crushed stone aggregate has a tendency to spread when being dumped into the excavation. Of course, once the stone has spread out of its intended position, its effectiveness is greatly diminished.
As earlier noted, an alternative to poured concrete foundations are permanent wood foundations using treated wood products. While more than 400,000 permanent wood foundations have been used in structures since the system was introduced in the early 1970's, it also has not received total acceptance in the building trade. Fear of the durability of treated wood foundations, the strength of such foundations, leaching, water destruction, etc. are some of the major concerns. While most of these concerns are unfounded and based upon improper usage of treated wood foundations, there is no doubt that their usage needs careful review and improvement. Therefore, while permanent wood foundations are not recommended for all uses, they can be used in frame construction where their use is superior to poured concrete. Engineered plywood foundations properly installed, for example, can be less expensive, more energy efficient, easier to install and more crack resistant and durable than concrete foundations. Thus, Permanent Wood Foundation (PWF) is an increasingly popular alternative to poured concrete and concrete block foundations. The PWF is especially attractive for homes with basements because the wood frame construction converts below-grade living spaces as warm and odor-free as the upstairs rooms. Use of PWF is similar to conventional wood-frame walls with one exception. PWF plywood and lumber is impregnated with preservatives to protect the foundation from termites and decay. As Permanent Wood Foundations have gained in use and popularity around the country, some have attempted to cast doubts about the system's benefits and quality. As earlier noted, most of these concerns are either unfounded or based upon mis-use of PWF construction.
Therefore, properly used PWFs and porous, crushed stone with an appropriate drainage system could greatly enhance their usage in the building industry.